Apple is right to seek a decisive court ruling against rival Samsung because "business is war" and litigation is powerful "weaponry" that should always be used against the competition, millionaire businessman Kevin O'Leary told CNBC on Tuesday.

"If you get an opportunity to go to court and actually hurt your competitor with a ban on their product, it's like pouring boiling water and salting the earth their offices are on," said O'Leary, star of the hit entrepreneur-based reality show "Shark Tank." "This is wonderful stuff if you can pull it off."

The two smartphone makers returned to court on Tuesday for opening statements in their long-running patent battle. An Apple attorney told jurors the company deserves about $2 billion from Samsung for copying the iPhone, but a Samsung lawyer said Apple was merely seeking to make up for losing share in the smartphone market.

Jurors awarded the iPhone maker about $930 million after a 2012 trial in San Jose, Calif., but Apple failed to persuade a U.S. District Court judge to issue a permanent injunction against the sale of Samsung phones.

"If I were an Apple shareholder, I would wish them to win this and ban the Galaxy series of phones," said O'Leary on "Squawk on the Street." "The likelihood is low, but at the same time, it's a great strategy if you think you can do some damage to your competitor's brand."

Asked by CNBC's Carl Quintanilla whether businesses should really file suit against rivals for a competitive advantage rather than to solely settle a legitimate claim, O'Leary answered with an emphatic, "Absolutely."

"There's nothing wrong with this strategy. You should put this in everybody's income statement. You're going to litigate everybody, every time you can. That's what makes it work," O'Leary said. "At the end of the day if you are lucky, maybe lucky that you could ban a couple of phones, this could add to your earnings and that's what you're supposed to be doing as a CEO."